US7285786B2 - High-resolution scintillation screen for digital imaging - Google Patents

High-resolution scintillation screen for digital imaging Download PDF

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Publication number
US7285786B2
US7285786B2 US11/222,605 US22260505A US7285786B2 US 7285786 B2 US7285786 B2 US 7285786B2 US 22260505 A US22260505 A US 22260505A US 7285786 B2 US7285786 B2 US 7285786B2
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cells
light
cellular
coupled
microscope
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US20070057195A1 (en
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Gary R. Sims
James J. Cook
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Spectral Instruments Inc
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Spectral Instruments Inc
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Assigned to SPECTRAL INSTRUMENTS, INC. reassignment SPECTRAL INSTRUMENTS, INC. ASSIGNMENT OF ASSIGNORS INTEREST (SEE DOCUMENT FOR DETAILS). Assignors: COOK, JAMES J., SIMS, GARY R.
Priority to PCT/US2006/034656 priority patent/WO2007030499A2/fr
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J37/00—Discharge tubes with provision for introducing objects or material to be exposed to the discharge, e.g. for the purpose of examination or processing thereof
    • H01J37/02—Details
    • H01J37/244—Detectors; Associated components or circuits therefor
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01T—MEASUREMENT OF NUCLEAR OR X-RADIATION
    • G01T1/00—Measuring X-radiation, gamma radiation, corpuscular radiation, or cosmic radiation
    • G01T1/16—Measuring radiation intensity
    • G01T1/161—Applications in the field of nuclear medicine, e.g. in vivo counting
    • G01T1/164—Scintigraphy
    • G01T1/1641—Static instruments for imaging the distribution of radioactivity in one or two dimensions using one or several scintillating elements; Radio-isotope cameras
    • G01T1/1644—Static instruments for imaging the distribution of radioactivity in one or two dimensions using one or several scintillating elements; Radio-isotope cameras using an array of optically separate scintillation elements permitting direct location of scintillations
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J37/00—Discharge tubes with provision for introducing objects or material to be exposed to the discharge, e.g. for the purpose of examination or processing thereof
    • H01J37/26—Electron or ion microscopes; Electron or ion diffraction tubes
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J2237/00—Discharge tubes exposing object to beam, e.g. for analysis treatment, etching, imaging
    • H01J2237/244—Detection characterized by the detecting means
    • H01J2237/2443—Scintillation detectors
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J2237/00—Discharge tubes exposing object to beam, e.g. for analysis treatment, etching, imaging
    • H01J2237/244—Detection characterized by the detecting means
    • H01J2237/24455—Transmitted particle detectors
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J2237/00—Discharge tubes exposing object to beam, e.g. for analysis treatment, etching, imaging
    • H01J2237/244—Detection characterized by the detecting means
    • H01J2237/2446—Position sensitive detectors
    • H01J2237/2447—Imaging plates

Definitions

  • This invention is related in general to the field of optical screens.
  • it relates to scintillation screens converting high-energy electrons to photons used in transmission electron microscopy.
  • CCD charged-coupled-device
  • the conversion is typically achieved with the use of a so-called scintillator, which is a layer of appropriate material—such as one of the specific phosphors used in the art—that is directly illuminated by the high-energy primary electrons forming the image in the TEM and that generates photons in response to such irradiation.
  • the photons are later relayed to the CCD camera using conventional means, the most common being optical-lens or fiber-optic systems, as seen in FIGS. 1A and 1B .
  • the scintillating phosphor layer is usually formed and contained separately from the optics, as shown in FIG. 1A , while in fiber-optic (FO) based systems it is usually deposited directly on an appropriately prepared input surface of the FO bundle, as seen in FIG. 1B .
  • FO fiber-optic
  • the light distribution L significantly exceeds the extent of a single FO channel, as each electron e ⁇ impinging on the scintillating layer S delivers corresponding photons to the CCD detector by not one but several FO channels.
  • several CCD pixels are illuminated by the image of the single electron due to random scattering of the electron (as well as generated X-rays and photons) in the scintillating layer S and overall image resolution is correspondingly decreased. It is clear, therefore, that only when the light distribution L and the CCD pixel have comparable sizes the digital imaging provided by the CCD is optimized.
  • the invention consists of discretizing the scintillating screen by structuring it not as a continuous layer of scintillating material but as a set of scintillating cells arranged in a particular cell pattern.
  • the pattern is selected so that it judiciously corresponds to the configuration of discrete elements in the receiving portion of the optical system, such the pattern of CCD pixels or the cross-sectional pattern of FO channels in the input portion of an FO means of light delivery to a CCD detector.
  • the light distribution generated in each scintillating cell does not extend beyond that cell, thus minimizing the imaging resolution loss due to scattering.
  • Such a discretized scintillator screen may be fabricated first by creating a cellular structure on an appropriate carrying surface and then by filling the cells with scintillating material.
  • the phosphor-containing cells are fabricated in such a fashion that there is at least a one-to-one optical correspondence between each cell and each imaging channel of the TEM system.
  • the cells may be fabricated in a stand-alone self-supporting structure and judiciously positioned to be optically conjugate with the pixels of the CCD-detector.
  • all phosphor-containing cells are fabricated from material that either significantly absorbs or reflects photons.
  • the light generated within the phosphor in each cell is fully contained within the boundaries of the cell, it is blocked from propagating into neighboring cells, and it is directly coupled into and delivered to CCD-detector pixel by corresponding FO channels on top of which the cell has been fabricated. Any cross-talk in the scintillator is therefore avoided, as well as imaging-resolution loss due to light coupling into the optical system.
  • FIG. 1A is a schematic illustration of a conventional lens-coupled CCD imaging system for transmission electron microscopy.
  • FIG. 1B is a schematic illustration of a conventional fiber-optics coupled system for transmission electron microscopy.
  • FIG. 2 is a schematic representation of the process of resolution loss occurring upon coupling of light generated in a conventional scintillator by a single electron in a fiber-optic light delivery system.
  • FIG. 3 is a scanning electron microscopy (SEM) image of a cellular scintillator structure according to the invention.
  • FIG. 4 is a schematic perspective view of a portion of a fiber-optic based imaging system according to the invention.
  • FIG. 5 is an elevational side view of the fiber-optic system of FIG. 4 .
  • FIG. 6 is a schematic section of the scintillating screen of the invention used in a lens-based TEM.
  • FIG. 7 is an elevational sectional view of an alternative embodiment of the invention used in a fiber-optic based TEM.
  • FIG. 8 is an elevational sectional view of an embodiment of the invention used in an X-ray imaging system.
  • the light generated within each cell is coupled directly to corresponding imaging channels of the system and delivered through those channels to a predetermined pixel (or set of pixels) of a CCD detector.
  • This physical and optical pairing of scintillator cells and corresponding image-forming channels of the TEM system limits the off-axis distribution of the light produced by each electron within the scintillator to the dimension of the cell, which is matched in some desirable proportion to the dimension of a corresponding imaging channel. Consequently, the light registration is restricted to a single corresponding pixel of the CCD detector.
  • the term “opaque” is used in this disclosure to mean not previous to radiant energy, especially light.
  • the term “transparent” is used to mean having the property of transmitting light without appreciable scattering.
  • the term “non-transmissive” is used to mean either opaque or reflective, as this term in conventionally used in the art.
  • the term “optical channel” is used to refer to any optical element, such as a lens or a fiber, used to transmit light from the scintillator to the light detector of a system.
  • the terms “scintillator” and “scintillator material” are used to refer to a material capable of generating visible light in response to incident high-energy electrons or X-ray radiation.
  • FIG. 3 is an SEM image of a typical cellular structure used to manufacture a TEM scintillator layer according to the invention.
  • the scintillator structure is formed in a layer of opaque material.
  • the cellular structure 20 may be fabricated on the input surface 21 of the FO bundle 22 of an FO-based TEM digital imaging system.
  • An appropriately thick film 26 of opaque material (such as titanium—Ti) is first deposited, or otherwise attached, and then a pattern of through-holes 28 in created in the film.
  • the film 26 could also be first patterned and then attached to the input surface 21 .
  • the dimensions and the pattern of the holes 28 are preferably selected to match directly the dimensions and the cross-sectional pattern of the FO channels 30 in the FO bundle 22 .
  • the diameters of the optical fibers typically used in current TEM systems are about 3 ⁇ m to 12 ⁇ m, such unique one-to-one correspondence between the holes 28 and channels 30 is difficult to achieve in practice. Therefore, inasmuch as the main concern is directed to ensuring that the system resolution is limited by the CCD pixels (which vary in size between about 9 ⁇ 9 ⁇ m 2 and 24 ⁇ 24 ⁇ m 2 ), the dimensions of the holes 28 are normally chosen to be smaller than the CCD pixels.
  • the film 26 may be formed by various deposition methods well known in the art, such as vacuum deposition; alternatively, a Ti foil may be glued to the surface 21 .
  • the through-holes 28 can be produced, for example, by high-aspect bulk micro-machining, as described by M. F. Aimi et al. in Nature Materials, v. 3, pp. 103-105. As a result, a set of cells 32 , patterned to uniquely correspond to the pattern of the FO bundle 22 , is formed on the top surface 21 of the bundle.
  • the cells 32 are then filled with a scintillating material and may be appropriately covered with a protective, preferably reflective layer 34 (for example, with a thin Al foil) to complete the manufacture of the cellular scintillating screen 36 of the invention ( FIG. 5 ).
  • a protective, preferably reflective layer 34 for example, with a thin Al foil
  • Al foil is not only to reflect back into the cell the photons generated in the phosphor, but also to ground the scintillator and therefore prevent it from becoming electrically charged and repelling the incident electron flux.
  • the cells 32 of the screen are fabricated directly on top of and centered with respect to the corresponding FO channels 30 and are separated from each other by opaque walls 38 , as seen in FIGS. 3 and 5 . Consequently, the light distribution L generated by the incident flux of electrons e ⁇ in the scintillating material in each cell is prevented from spreading beyond the perimeter of the cell and is coupled directly to the single corresponding FO channel. This eliminates any coupling of the light to multiple FO channels, as compared to the situation illustrated FIG. 2 , and correspondingly any cross-talk among FO channels. Therefore, the imaging resolution of the system 40 is optimized. For convenience of illustration, these figures show the scintillator cells coupled to two FO channels, but it is understood that in practice such precise correspondence would be difficult to achieve and therefore unlikely.
  • FIG. 6 An alternative embodiment 42 of the invention for a lens-coupled imaging system is illustrated in FIG. 6 .
  • a cellular scintillating screen 50 is shown as a stand-alone component comprising a layer of phosphor-bearing cells 32 on a sheet 51 of transparent glass and an aluminum foil 34 structurally supported by an appropriate frame 52 .
  • the cells 32 are again formed from opaque material (such as Ti) and judiciously sized to a predetermined correspondence with the dimensions of the CCD-pixels to which they are to be coupled. All cells 32 are preferably distributed uniformly across the screen according to the pixel pattern of the corresponding CCD detector in the TEM system (not shown in FIG. 6 ).
  • the light distribution L generated by incident electrons in the phosphor contained within any cell of the structure is completely contained within the cell and is directly imaged by the lens (not shown) onto a uniquely corresponding pixel of the CCD detector (also not shown).
  • the lens not shown
  • the CCD detector also not shown
  • CMOS or CID detectors could be used instead of CCDs.
  • a scintillating-material-bearing cellular structure 62 can be first formed with any suitable material on the input surface 21 of the FO bundle 22 (for example, by etching or high-aspect bulk micromachining processes), and then appropriately overcoated with a film 64 of opaque material (such as Ti). It is also clear that the distribution and size of the cells in the screen of the invention do not have to be uniform throughout the screen, but may be varied to match the configuration of the system's optics or detector, or to meet any other requirement of the system.
  • the invention has been shown and described in the context of conventional transmission electron microscopy, it is recognized that the same concept could be adapted by those skilled in the art to any system wherein a high-energy electron flux or X-ray radiation is converted into photons by a scintillation material.
  • the invention could be practiced in applications involving indirect X-ray imaging with a typical silicon detector (such as a CCD, a CMOS, or a CID detector).
  • the scintillator material that converts the incident flux of X rays to photons is pixelated, according to the invention, and the photons are delivered optically from the scintillator to the detector. As illustrated in the system 70 shown in FIG.
  • a pixelated structure 36 of cells 32 is formed with any suitable opaque material (such as Ti) on the input surface 21 of a FO bundle 22 coupled to a detector. (Alternatively, the structure 36 may be formed directly on the input surface of the detector.) As a result, the columnar structure of the cells 36 acts as a scintillating waveguide-like structure that guides the photons generated by the incident flux of X rays within the scintillator 72 of each cell towards the FO bundle 22 .
  • the invention overcomes the prior-art requirement that anisotropic scintillators be used, such as cesium iodide, sodium iodide, zinc sulfide, or calcium fluoride, in the form of long, oriented, needle-like columns, as described in U.S. Publication No. 20050089142.
  • the arrangement of the invention additionally reduces the light scatter within the scintillator of the X-ray imaging system 70 as compared to conventional systems that contain randomly oriented scintillator material.

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  • Physics & Mathematics (AREA)
  • Health & Medical Sciences (AREA)
  • Analytical Chemistry (AREA)
  • Chemical & Material Sciences (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Medical Informatics (AREA)
  • Nuclear Medicine, Radiotherapy & Molecular Imaging (AREA)
  • Optics & Photonics (AREA)
  • General Health & Medical Sciences (AREA)
  • General Physics & Mathematics (AREA)
  • High Energy & Nuclear Physics (AREA)
  • Molecular Biology (AREA)
  • Spectroscopy & Molecular Physics (AREA)
  • Biomedical Technology (AREA)
  • Engineering & Computer Science (AREA)
  • Measurement Of Radiation (AREA)
  • Analysing Materials By The Use Of Radiation (AREA)
US11/222,605 2005-09-09 2005-09-09 High-resolution scintillation screen for digital imaging Expired - Fee Related US7285786B2 (en)

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US11/222,605 US7285786B2 (en) 2005-09-09 2005-09-09 High-resolution scintillation screen for digital imaging
PCT/US2006/034656 WO2007030499A2 (fr) 2005-09-09 2006-09-06 Écran scintillant haute résolution pour imagerie numérique

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Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US11355309B2 (en) * 2018-08-02 2022-06-07 Applied Materials Israel Ltd. Sensor for electron detection
US11531123B2 (en) * 2018-04-24 2022-12-20 Hamamatsu Photonics K.K. Radiation detector comprising fiber optic plates and image sensors, radiation detector manufacturing method, and image processing method

Families Citing this family (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN103151232B (zh) * 2013-03-08 2015-10-14 中国人民解放军南京军区福州总医院 一种侧装光纤耦合透射电镜数字成像方法及其装置
US20220173149A1 (en) * 2020-12-02 2022-06-02 Star Tech Instruments, Inc. Beam imaging and profiling device
CN113126138B (zh) * 2021-04-23 2022-11-11 重庆大学 一种多层耦合结构高分辨闪烁屏制造方法及其闪烁屏

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20050089142A1 (en) 2003-10-27 2005-04-28 Marek Henry S. Scintillator coatings having barrier protection, light transmission, and light reflection properties
US20060169901A1 (en) * 2004-12-08 2006-08-03 The Regents Of The University Of California Direct collection transmission electron microscopy

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20050089142A1 (en) 2003-10-27 2005-04-28 Marek Henry S. Scintillator coatings having barrier protection, light transmission, and light reflection properties
US20060169901A1 (en) * 2004-12-08 2006-08-03 The Regents Of The University Of California Direct collection transmission electron microscopy

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
M.F. Aimi et al. in Nature Materials, v. 3, pp. 103-105, copy not available.

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US11531123B2 (en) * 2018-04-24 2022-12-20 Hamamatsu Photonics K.K. Radiation detector comprising fiber optic plates and image sensors, radiation detector manufacturing method, and image processing method
US11355309B2 (en) * 2018-08-02 2022-06-07 Applied Materials Israel Ltd. Sensor for electron detection

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US20070057195A1 (en) 2007-03-15
WO2007030499A2 (fr) 2007-03-15

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